Acquisitions and Divestitures (Summary of Allocation of Total Purchase Consideration) (Details) $ in Millions	12 Months Ended
	Jul. 28, 2018 USD ($) acquisition	Jul. 29, 2017 USD ($) acquisition	Jul. 30, 2016 USD ($) acquisition
Business Acquisition [Line Items]
Purchase Consideration	$ 3,218	$ 3,637	$ 3,400
Net Tangible Assets Acquired (Liabilities Assumed)	334	(186)
Purchased Intangible Assets	867	878
Goodwill	$ 2,017	2,945
Number of business combinations (acquisition) | acquisition	8		12
Viptela
Business Acquisition [Line Items]
Purchase Consideration	$ 497
Net Tangible Assets Acquired (Liabilities Assumed)	(18)
Purchased Intangible Assets	180
Goodwill	335
Springpath
Business Acquisition [Line Items]
Purchase Consideration	248
Net Tangible Assets Acquired (Liabilities Assumed)	(11)
Purchased Intangible Assets	160
Goodwill	99
BroadSoft
Business Acquisition [Line Items]
Purchase Consideration	2,179
Net Tangible Assets Acquired (Liabilities Assumed)	353
Purchased Intangible Assets	430
Goodwill	1,396
Accompany
Business Acquisition [Line Items]
Purchase Consideration	222
Net Tangible Assets Acquired (Liabilities Assumed)	6
Purchased Intangible Assets	55
Goodwill	161
CloudLock
Business Acquisition [Line Items]
Purchase Consideration		249
Net Tangible Assets Acquired (Liabilities Assumed)		0
Purchased Intangible Assets		36
Goodwill		213
AppDynamics
Business Acquisition [Line Items]
Purchase Consideration		3,258
Net Tangible Assets Acquired (Liabilities Assumed)		(175)
Purchased Intangible Assets		785
Goodwill		2,648
MindMeld
Business Acquisition [Line Items]
Purchase Consideration		104
Net Tangible Assets Acquired (Liabilities Assumed)		(11)
Purchased Intangible Assets		51
Goodwill		64
Others
Business Acquisition [Line Items]
Purchase Consideration	72	26
Net Tangible Assets Acquired (Liabilities Assumed)	4	0
Purchased Intangible Assets	42	6
Goodwill	$ 26	$ 20
Number of business combinations (acquisition) | acquisition	4	4